Fabricated snack products are popular with consumers throughout the world. Fabricated snack products are made from potato, corn, and a variety of cereal grains. Exemplary snack products include Ripplins.TM. brand potato snacks manufactured by the Keebler Co., Pringles.TM. brand potato snacks manufactured by the Proctor & Gamble Co. and Doritos.TM. brand tortilla chips manufactured by Frito-Lay.
These snack products are typically fabricated from some type of dough. The dough usually contains a primary ingredient, such as potato, corn, or cereal based solids, mixed with or containing water, spices and various other dry ingredients. The dry ingredients may include starches in powder, granular, or flake form, added as a binder for the dough, or to produce a certain texture or expansion in the cooked snack product. By way of example, a basic formula for a fabricated potato snack includes: potato flakes, raw potato starch, ground dehydrated potatoes, sugar, salt and various flavoring ingredients.
During a testing process, the dough ingredients are mixed in predetermined quantities, under controlled conditions, to form a batch of dough having a desired moisture content and consistency. The dough is then formed into a desired shape (e.g. chips, rings) prior to cooking. Cooking may be by frying or baking at a predetermined temperature for a predetermined time. Forming of the individual dough pieces may be accomplished using a piston extrusion apparatus that forces the dough through a die. Alternately, the dough can be sheeted to a predetermined thickness and then cut into uniform small pieces having a desired shape. Piston extrusion is preferred, however, because it provides more consistent control in the forming of the test product.
One goal of any process for making fabricated snacks is to be able to consistently produce certain important characteristics in the snack product which affect the quality of the snack product and its success in the market. Such important characteristics of a snack product include flavor, color, thickness, moisture content, texture, fat content and degree of bubbling.
Some characteristics of a snack product are intended to achieve a certain perception by the consumer. As an example, the internal expansion of a snack product influences the texture, mouth feel, and crispness of the product. A product, such as a fabricated potato snack, which is intended to be crisp like a conventional potato chip, must therefore be expanded to the same degree.
Expansion occurs during the frying or baking process as the water present in the snack dough escapes from the formed dough pieces. The expansion of the snack product is often expressed as the ratio of the snack thickness to the original dough thickness. Expansion during frying is a function of the quantity and type of the internal bubbling that occurs during the frying or baking process, which in turn is a function of many factors including, for example, the moisture and free gelatinized starch content of the snack dough. For baked products, leavening systems and baking conditions are used to achieve a desired expansion.
Many characteristics of a snack product can be measured directly, such as thickness, moisture content, color and fat content. Other characteristics, such as texture, flavor and bubble content, require a more subjective system of evaluation. In this regard, various rating and evaluation techniques have been developed in the art to quantify important characteristics of fabricated snack products. U.S. Pat. No. 4,931,303 to Holm et al., which is incorporated herein by reference, describes an exemplary system for evaluating the bubble size and bubble distribution in a fried snack product.
Different methods have also been developed for evaluating doughs used to make snack products. The previously cited patent to Holm et al. describes a rating system for evaluating the consistency of a snack product dough. Under this rating system, various visual and manual characteristics are used to quantify a dough's consistency. A dough receives a rating from Type 1 to Type 9. A Type 1 dough has a dry/friable consistency and can be squeezed into a ball by hand only with difficulty. A Type 9 dough has a sticky/adhesive consistency and is similar to bread dough. Various intermediate doughs (e.g., Types 2-8) have other characteristic consistencies as shown as follows.
1. Dry, friable, powdery dough--can be squeezed by hand into a ball only with difficulty. PA1 2. Dry, friable--more easily squeezed into a ball. PA1 3. Easily squeezed into a ball which breaks apart when dropped. PA1 4. Friable--some small agglomerates remain after mixing. PA1 5. Borderline friable/cohesive, discharged with ease from mixer--many random agglomerates after mixing. Hand-formed ball does not break easily when dropped. PA1 6. Predominantly agglomerates easily molded into ball which feels wet--discharged from mixer with difficulty. PA1 7. All large agglomerates--discharged with difficulty from mixer. Hand-formed ball does not break when dropped. PA1 8. Completely uniform, cohesive mixture--discharged from mixer as a single non-adhesive dough. PA1 9. Uniform adhesive dough similar to bread dough--cannot be discharged from mixer except as single unit which sticks to fingers.
In general, the different methods for evaluating a snack product developed in the industry thus far have been directed to evaluating either the characteristics of the fabricated snack product or the dough used to make the snack product. These characteristics, however, are dependent on the properties of the individual ingredients which make up the snack product or dough.
As an example, raw or pregelatinized starches used in the formulation of snack products may have different properties which will affect the characteristics of the snack product. Specifically, starches that vary in water absorption, gelatinization temperature or degree of retrogradation will cause structural variations in snack products which contain the starch ingredients. To date, however, no test has been developed that is effective in predicting the performance of a particular starch as an ingredient in a snack product.
The free gelatinized starch content of a snack ingredient may also affect the characteristics of the finished snack product. The texture of fried fabricated potato snack products is particularly affected by the free gelatinized starch content. One widely used grading system for potato solids, known as the "iodine index", measures the "free soluble starch" contained in potato flakes. As disclosed in U.S. Pat. No. 3,998,975 to Liepa, the iodine index may be useful in some applications for predicting dough formulations for sheeted potato-based snack products. This index, however, has not proven to be a reliable method for predicting important characteristics of a finished snack product. In addition, its use is mainly limited to potato snacks.
In light of this, it would be desirable to have a reliable method for evaluating the functional properties of the ingredients which are used in fabricating snack products. This evaluation could then be used to predict the performance of the different ingredients of a fabricated snack product and the characteristics of the finished product.
This need is compounded by the lack of equipment in the snack industry suitable for reproducing fabricated snack products in the laboratory. In particular, small scale extrusion apparatus suitable for consistently extruding dough pieces for cooking are generally not available. In the past, laboratory extrusion apparatus has typically been of a make-shift nature. A modified pasta press, for example, may sometimes be used in a laboratory setting for extruding small batches of dough. Such makeshift extrusion apparatus, however, cannot efficiently extrude a snack food dough over a range of dough consistencies. This is a problem because one test ingredient may produce a soft, flowable dough, whereas another test ingredient may produce a firm, non-flowable dough.
The uniformity of the extruded dough is also a problem. Most extrusion apparatus typically depend on a pressure driven piston to force the dough through a die orifice. With a pressure driven piston, the pressure and flow rate generated during the extrusion process vary as a function of a dough's consistency. A dough with a Type 1 consistency will require more pressure to extrude than a dough with a Type 6 consistency. At the same extrusion pressure, the rate of extrusion will vary markedly with different dough consistencies.
Furthermore, a dough under test may not have a perfectly uniform consistency. This will cause the extrusion pressure and the rate of extrusion to fluctuate. The characteristics of the extruded dough pieces (e.g. density, texture, thickness) will thus not be uniform. In order to provide reliable comparisons between different snack product dough pieces, however, an extrusion apparatus must produce a substantially uniform extrudate from a dough, regardless of the consistency of the dough. In general, a laboratory sized extrusion apparatus, suitable for extruding uniform dough pieces over a range of dough consistencies is not available.
In view of these and other problems, there is a need in the art for reliable methods and apparatus for testing and evaluating the ingredients used in fabricated snack products. Accordingly, it is an object of the present invention to provide a method and apparatus for testing and evaluating ingredients for fabricated snack products.
It is a further object of the present invention to provide a method for testing and evaluating ingredients for snack products, that is simple, reliable, and in which process parameters can be precisely controlled during the formation of snack product test pieces.
It is yet another object of the present invention to provide a laboratory extrusion apparatus suitable for extruding and cutting snack product dough pieces having a uniform size and shape that permits testing and precise evaluation of individual ingredients.
It is a further object of the present invention to provide a laboratory extrusion apparatus for extruding substantially uniform snack dough pieces from small batches of dough at a constant rate, regardless of the dough's consistency, and immediately frying the dough pieces for evaluation.